DE102016218164A1 - Method for determining the minimum permissible volume flow of a volume-controlled electrically driven auxiliary pump of a transmission of a motor vehicle - Google Patents

Abstract

A method for determining the minimum permissible volume flow of a volume-controlled electrically driven auxiliary pump of a transmission of a motor vehicle is proposed in the context of which the transmission leakage volume requirement is determined on the basis of the deviation of the fast filling time of at least one switching element from the rapid filling time in the case of a "standard leakage transmission" which must be covered in order to ensure the transmission functionality, is calculated from the transmission leakage volume demand, the minimum allowable flow rate of volume controlled electrically driven auxiliary pump.

Description

The invention relates to a method for determining the minimum permissible volume flow of a volume-controlled electrically driven auxiliary pump of a transmission of a motor vehicle, according to the preamble of patent claim 1.

In transmissions having an electrically driven auxiliary pump, the electrically driven auxiliary pump is usually operated with an unnecessarily high power consumption or with an unnecessarily high volume flow, because the worst-case case must be covered. This disadvantageously increases fuel consumption for over 99% of the vehicles because, in the prior art, to determine the volumetric flow of a volume controlled, electrically driven booster pump, the maximum transmission leakage, i. the lubricating oil requirement of the gear unit and the hydraulic gearbox control of the series production is taken into account and used.

Gear shift elements of gearboxes usually have a movable in a piston chamber switching piston, which is applied to a disk set. In order to perform a desired circuit, the substantially air-filled piston chamber must be filled with oil. Subsequently, the piston is applied to the disk pack. As part of a fast filling phase, the switching element is filled with oil, whereas in a Füllausgleichsphase the piston is applied with a low load

From the prior art it is known to adapt the fast filling time of the switching elements of a transmission; In this case, starting from a center or standard transmission, a rapid filling time is applied and an adaptation time offset is determined. The fast filling time corresponds to the time in which a switching element can be filled at the corresponding applied pressure. This time is derived from a volume balance, since it is needed to cover the gearbox leakage with the known pump power and to fill the switching element with the excess volume or to overcome the clearance of the piston of the switching element. If the clearance of the piston changes due to the setting behavior of the components and / or wear, the fast filling time is increased. Furthermore, the fast filling time becomes longer if the gearbox leakage is greater while the clearance is unchanged.

From the DE 195 46 292 A1 the applicant is a method for automated tuning of the filling and application process of hydraulically actuated and hydraulically or electronically individually controllable switching elements of a transmission out, in the context of the filling and application process is divided into a Schnellfüllphase and Füllgleichgleichsphase and at least one Schnellfüllzeit, a Fast filling pressure, a Füllausgleichszeit and a Füllausgleichsdruck as a parameter. Here, two of the four parameters are specified, wherein for the other parameters by means of a predetermined time-dependent pressure curve, in which the Schnellfüllphase and the Füllausgleichsphase a pressure increase phase follows, an optimal value is first determined for a first parameter to be optimized, starting from a respective predeterminable Initial value, this is gradually changed until a speed change occurs with or before the beginning of the pressure rise phase. The further parameter to be optimized is determined by incrementally changing this parameter at the optimum value of the first parameter to be optimized and starting from the respective predefinable initial value until a speed change occurs before or at least approximately simultaneously with the beginning of the pressure rise phase.

Furthermore, goes from the DE 198 26 097 A1 Applicant, a method for correcting the filling volume of pressure-actuated clutches in vehicle transmissions out, wherein the clutches are each actuated by a switching element, which applies a filling pressure to the clutch during a filling time. In the known method, it is provided that a computing device determines a current load state for the switching element from predetermined process variables of preceding switching processes and that a filling time stored in a memory device is derived for the determined current switching state, which was previously determined by empirical preliminary tests.

From the DE 10 2005 042 933 A1 the applicant is a method for controlling and regulating an automatic transmission of a vehicle with a running of a speed of a prime mover varying delivery pump means of a hydraulic system hydraulically actuated switching elements for setting different gear ratios and with an electric transmission control known, wherein the switching elements respectively during a Schnellfüllphase so be subjected to a Schnellfülldruck that they are performed by an incompletely pre-filled operating condition in the direction of a fully pre-filled operating condition. In this case, a duration of a fast filling phase of a switching element is changed as a function of an operating state of the automatic transmission and / or as a function of a delivery volume of the pump device by varying the rapid filling pressure

Furthermore, goes from the DE 10 2008 001 277 A1 the Applicant a method for operating a drive train of a motor vehicle, wherein the drivetrain comprises at least one hybrid drive with an internal combustion engine and an electric motor, a clutch connected between the internal combustion engine and the electric motor, a transmission arranged between the hybrid drive and an output, to which a main hydraulic pump and an auxiliary hydraulic pump are assigned, and an internal or external gear drive element. It is provided that the auxiliary hydraulic pump is operable in two discrete operating points, wherein the first operating point only serves to provide a basic supply to compensate for the leakage in the transmission and the second operating point ensures the oil supply to the transmission when starting the vehicle electric. The auxiliary hydraulic pump is turned on when a switch-on criterion is met and then first operated in its first operating point, wherein a switchover to the second operating point, when the driver releases the brake pedal, when a torque request is detected or when a Anfahrmomentenschwelle is exceeded.

From the DE 10 2008 041 402 A1 The applicant is a powertrain of a motor vehicle is known, with a hybrid drive, which includes an internal combustion engine and an electric motor with a arranged between the hybrid drive and an output gear, wherein the transmission of a mechanically driven by a shaft main hydraulic pump and an electric motor driven by a pump motor auxiliary hydraulic pump assigned. It is provided that the auxiliary hydraulic pump is turned on when using a leakage model, which takes into account the mechanically driven main pump and an electro-hydraulic control unit, was determined analytically that the currently required actual oil volume demand can not be covered by the main pump.

The present invention has for its object to provide a method for determining the minimum allowable flow rate of a volume-controlled electrically driven auxiliary pump of a transmission of a motor vehicle. The minimum permissible volume flow is the volume flow through which, on the one hand, the minimum amount of lubricating oil required is made available and, on the other hand, no more lubricating oil is supplied as required.

This object is solved by the features of patent claim 1. Further embodiments and advantages of the invention will become apparent from the dependent claims.

Accordingly, a method for determining the minimum permissible volume flow of a volume-controlled electrically driven auxiliary pump of a transmission of a motor vehicle is proposed, in the context of which the transmission leakage volume requirement is determined on the basis of the deviation of the rapid filling time of at least one switching element from the rapid filling time in the case of a "standard leakage transmission" , which must be covered in order to ensure the transmission functionality, is calculated from the transmission leakage volume demand, the minimum allowable flow rate of the volume controlled electrically driven auxiliary pump, the transmission leakage volume requirement is determined by a known clearance of the switching elements of the transmission, characterized in that Starting from a "standard leakage transmission", in which the transmission leakage is known, each switching element is assigned a rapid filling time offset from the rapid filling time adaptation, wherein a deviation of the rapid filling time from a speed filling time offset associated with a switching element means a deviation in the leakage behavior of the transmission and is taken into account in the control of the electrically driven auxiliary pump, in order to ensure that the electrically driven auxiliary pump delivers the minimum necessary volume flow and does not exceed this plus an optional, predetermined offset. According to the prior art, the clearance is detected at the completion assembly; In order to carry out the method according to the invention, the clearance value at the final test stand must be known or assigned to a transmission.

A deviation from a switching element associated Schnellfüllzeitoffset directly means a deviation in the leakage behavior of the transmission and is taken into account in the delivery balance of the electrically driven auxiliary pump so that the pump provides the one hand, the minimum necessary amount of lubricating oil and on the other hand no longer supplies lubricating oil as required. Based on the deviation, the additional transmission leakage volume requirement based on the "standard leakage transmission" is determined.

In a further development of the invention, every possible clearance of a switching element in a grid, e.g. 0.1mm, assigned a fast filling time, which is determined in the application with a "standard leakage gear.

Furthermore, according to a development of the invention, the deviations of the rapid filling time offsets of all the shifting elements of the transmission can be averaged in order to determine the transmission leakage volume requirement.

If the clearance of the switching elements is not known, the deviation of the fast filling time according to the current fast filling time offset from the time actually required for rapid filling of a switching element in a "standard leakage gear" detected for all the switching elements of the transmission, the smaller the deviation, the lower the gear cover and the clearance of the respective switching element. A worst-case scenario in which the clearance of a switching element assumes a minimum value and the rapid filling time offset assumes a maximum value would result in the maximum volume flow of the auxiliary pump being required because the deviation is caused by a high gear leakage.

In order to determine the gearbox leakage, the smallest deviation from the time required for fast filling of a switching element in a "standard leakage gearbox" is used, whereby it is assumed that the deviation is due to the additional gearbox leakage volume requirement in relation to the "standard leakage Transmission is conditional.

The invention is based on the finding that during the rapid filling time of a switching element, the gearbox delivery quantity acts like a clearance expansion; The fast filling time of a switching element is longer with larger gear leakage quantity, since at a given volume flow of the auxiliary pump, the excess amount that is available for the purpose of Schell filling a switching element, due to the gearbox leakage is lower. The required rapid filling time or the fast filling time offset from the rapid filling time adaptation is therefore a measure of the gearbox leakage and the clearance. According to the invention, starting from a "standard leakage transmission" based on the adaptation time offset, it can be determined how large the transmission leakage is.

The inventive concept determines the leakage behavior of the transmission from the rapid filling time or the rapid filling time offset of at least one switching element. While only the clearance of the switching elements is counteracted by the Schnellfüllzeitadaption according to the prior art, it is recognized according to the invention from the Schnellfüllzeitadaption, with which minimum requirement the auxiliary pump must be operated to ensure sufficient lubrication in the present gearbox leakage. According to the prior art, to determine the volume requirement of a volume-controlled, electrically driven auxiliary pump, the maximum gear leakage of the series deviation is always taken into account.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 19546292 A1 [0005]
• DE 19826097 A1 [0006]
• DE 102005042933 A1 [0007]
• DE 102008001277 A1 [0008]
• DE 102008041402 A1 [0009]

Claims (4)

Method for determining the minimum permissible volume flow of a volumengeregelten electrically driven auxiliary pump of a transmission of a motor vehicle, characterized in that based on the deviation of Schnellfüllzeit at least one switching element of the Schnellfüllzeit at a "standard leakage transmission" the gear leakage volume requirement is determined, the covered must be in order to ensure the transmission functionality, which is calculated from the transmission leakage volume demand, the minimum allowable flow rate of the volume-controlled electrically driven auxiliary pump. Method for determining the minimum permissible volume flow of a volume-controlled electrically driven auxiliary pump of a transmission of a motor vehicle according to claim 1, characterized in that the transmission leakage volume requirement is determined with known clearance of the switching elements of the transmission characterized in that each switching element starting from a "standard leakage Gearbox "is assigned a Schnellfüllzeitoffset from the Schnellfüllzeit adaptation, wherein a deviation of the Schnellfüllzeit of a switching element associated Schnellfüllzeitoffset means a deviation in the leakage behavior of the transmission and wherein based on the deviation of the additional gear leakage volume requirement based on the" standard leakage gear " is determined. Method for determining the minimum permissible volume flow of a volumengeregelten electrically driven auxiliary pump of a transmission of a motor vehicle according to claim 2, characterized in that each possible clearance of a switching element in a grid is assigned a Schnellfüllzeit, which is determined by a "standard leakage transmission. A method for determining the minimum allowable flow rate of a volume controlled electrically driven auxiliary pump of a transmission of a motor vehicle according to claim 1, characterized in that when the clearance of the switching elements is not known, the deviation of the Schnellfüllzeit according to the current Schnellfüllzeitoffset of actually required for fast filling of a switching element Time is detected in a "standard leakage transmission" for all the switching elements of the transmission, where to determine the gearbox leakage, which is the smallest deviation to the time required for rapid filling of a switching element in a "standard leakage transmission" used It is assumed that the deviation is due to the additional gear leakage volume requirement related to the "standard leakage gear" and where based on this deviation, the additional gear leakage volume requirement based on the "standard leakage gear" determined becomes.